This invention relates to a wiring substrate having a semiconductor device mounted thereon and a module and an electronic device each using this substrate, and more particularly to a semiconductor chip carrier, module and electronic device for achieving an increase in speed of signal transmission in semiconductor devices.
Improvements have been made year after year in semiconductor chips responding to the strong requirements for higher integration, size enlargement, and greater speed of semiconductor chips mounted on semiconductor chip carriers. To be more concrete, the higher integration is achieved by increasing the element density in a chip by making the elements progressively more miniature, and enlarging the size of the chip. On the other hand, attempts have been made to obtain a higher speed of signal processing by realizing higher function of the elements and higher element density of the chip. However, the higher element density not only contributes to higher operation speed but also has an adverse effect of hindering the improvement of operation speed, which is becoming conspicuous in recent years. More specifically, as the higher the element density becomes, the wiring conductor width in the chip is getting narrower, which increases the wiring resistance, thus increasing the delay of signal transmission resulting from wiring reasons. This wiring delay has become an obstacle to realization of higher operation speed of semiconductor chips. An example of this is that the higher speed of the chip cannot be achieved unless the wiring for clock signal transmission, which can cause a signal delay, has low resistance in order to obtain operational synchronization with signals in the semiconductor chips.
In order to form a long wiring with low resistance in a chip, it is necessary to make improvements related to the material, width and thickness of wiring.
The substrate (hereafter referred to as a wiring substrate) on which a semiconductor chip is mounted expands the pitch of connection pads of semiconductor chips to facilitates connection to the wiring board. The wiring substrate often serves for sealing of the semiconductor chip.
As technology of this kind, there is "Hardware technology of the ultra-large processor group HITAC M-880" reported in Hitachi Hyouron "Vol. 73, No. 2, pp. 41-48 (1991-2)", for example.
Under this situation, it has conventionally necessary to achieve the higher speed of the semiconductor chip by the whole of a chip carrier including a chip. However, in achieving the higher speed of the semiconductor chip or chip carrier, it is essential to reduce the wiring delay which hinders the improvement of the signal processing speed as mentioned above.